Capillary tubes are required for a variety of different uses. For example, in the electronics sector, reed switches and transponders are welded in thin glass capillary tubes. In order for the function of such components, which in some cases are relevant to safety, not to be impaired, the cleanliness of the capillaries used has to meet stringent requirements.
The cleaning of capillary tubes, however, is an extremely difficult task. Thus, the cleaning medium, on account of the surface tension, is slow to penetrate into the capillaries and thus usually achieves an unsatisfactory cleaning result.
The cleaning of capillaries which are closed at one end, also known as scooping capillaries, poses particular problems. If such a scooping capillary is to be flooded with a cleaning medium, the cleaning medium usually penetrates only into the front region since the air which is enclosed in the region behind prevents the cleaning medium from passing through the entire volume of the capillary.
A series of methods are known for the purpose of cleaning capillaries.
Thus, for example, EP 1 237 665 discloses the operation of cleaning capillaries by means of a liquid which contains magnetic droplets. A significantly improved cleaning action is achieved by a changing magnetic field being applied.
DD 274 173 discloses a method of cleaning capillaries in which the capillary is cooled from outside in a nitrogen bath and a cryogenic liquid is forced through the capillary.
Also known in practice are mechanical methods in which a cleaning aid is forced through the capillary. Such mechanical methods, however, are not suitable for all types of capillaries. The known methods of cleaning capillaries involve extremely high outlay.
In particular the operation of cleaning scooping capillaries is possible only to an insufficient extent using methods which are known from the prior art.